[b]Of [/b][i]trilateral figures[/i][b], an [/b][i]equilateral triangle[/i][b] is that which has its three sides equal, an [/b][i]isosceles triangle[/i][b] that which has two of its sides alone equal, and a [/b][i]scalene triangle[/i][b] that which has its three sides unequal.[/b][br][br]We define triangles in two ways, by their sides and by their angles. When we define triangles by their sides (or legs) we are comparing how many sides are equal:[br][br]equilateral (equal lines) triangle: three equal sides[br][br]isosceles (balanced legs) triangles: two equal sides[br][br]scalene (unequal) triangle: no equal sides[br][br][b]Further, of [/b][i]trilateral figures[/i][b], a [/b][i]right-angled triangle[/i][b] is that which has a [i]right angle[/i], an [/b][i]obtuse-angled triangle[/i][b] that which has an [i]obtuse angle[/i], and an [/b][i]acute-angled triangle[/i][b] that which has its three [/b][i]angles acutes[/i][b].[br][br][/b]The second way we define triangles is by their angles and what the defining angle is in the triangle:[br][br]right triangle: contains one right angle (and two acute angles)[br][br]obtuse triangle: contains one obtuse angle (and two acute angles)[br][br]acute triangle: contains three acute angles

I have given you (temporarily) a new tool [icon]/images/ggb/toolbar/mode_distance.png[/icon], which you can use to measure side lengths of shapes by clicking on them. Using the figures you have been provided below, see if you can identify each triangle type.[br][br]HINT: Triangles can be labeled by their sides or by their angles, so a right triangle must also be either scalene or isosceles (why can't a right triangle be equilateral?) so each triangle will have two names.[br][br]Move the points around and see if it changes your labels.